Surge prevention device

ABSTRACT

A surge prevention valve may be used to prevent the formation of an initial surge of high pressure. The valve may be located, for example, between a high pressure gas cylinder and a medical pressure regulator. The valve is provided with first and second valves located within a housing and integrating a pressurization orifice. The initial opening of the valve in an axial direction enables gas to flow through the pressurization orifice at a first flow rate. The full opening of the valve in the axial direction enables the gas to flow through the second valve at a second flow rate, which is much higher than the first flow rate. The controlled pressurization of the gas through the orifice delays the time during which the gas reaches full recompression. The valve may be further provided with a vent for venting pressurized gas away from a nominally closed top surface of the lower valve element. The valve may be also provided with a valve inlet tube extending into a gas cylinder to prevent contaminants, particles and/or impurities from entering the valve.

The present application is a continuation of U.S. patent applicationSer. No. 10/188,366, filed Jul. 3, 2002 (now U.S. Pat. No. 6,910,504),which in turn is a continuation-in-part of U.S. patent application Ser.No. 10/034,250, filed Jan. 3, 2002 (now U.S. Pat. No. 6,901,962), whichis a continuation-in-part of U.S. patent application Ser. No.09/374,130, filed Aug. 9, 1999 (now U.S. Pat. No. 6,622,743). The entiredisclosures of U.S. patent application Ser. Nos. 10/188,366 and10/034,250 are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to a device for handling a gas,such as oxygen and nitrous oxide, under high pressure. The presentinvention also relates to a valve for controlling the flow of gas and toa system for reducing or preventing high pressure surge.

Known high pressure oxygen delivery systems are provided with an oxygencylinder, a cylinder valve and a pressure regulator. The oxygen cylindermay be charged with pure oxygen at a pressure of two thousand twohundred pounds per square inch (psi) or more in the United States andover three thousand psi in other countries. The valve is attached to thecylinder to stop the flow of oxygen to the regulator. The pressureregulator is designed to reduce the tank pressure to under two hundredpsi. Most pressure regulators in the United States reduce tank pressureto approximately fifty psi. Typical pressure regulators in Europe reducetank pressure to approximately sixty psi.

When the valves in the known oxygen systems are opened rapidly,undesirable high pressure surges may be applied to the pressureregulator. There is a need in the art for preventing such high pressuresurges, as well as increases in the temperature of the gas which mayresult in ignition. A similar problem may occur with respect to nitrousoxide supplied, for example, for dental procedures.

The risk of oxygen regulator failure may be higher for portable oxygensystems that are used in adverse environments and/or by untrainedpersonnel. Portable oxygen systems are used for emergency oxygendelivery at accident sites; for other medical emergencies, such as heartattacks; and for transporting patients. Homecare patients who use oxygenconcentrators as the main source of oxygen for oxygen therapy arerequired to have standby oxygen cylinders in case of power failures.Oxygen cylinders are also used to provide homecare patients withmobility outside the house. There is a need in the art for a valve thatcan be used easily in such portable systems and that reduces oreliminates the occurrence of high pressure surges. Other uses includehospitals, where oxygen cylinders are used to transport patients. Theyare also used as emergency backup systems.

Known surge suppression devices are illustrated in U.S. Pat. No.3,841,353 (Acomb), U.S. Pat. No. 2,367,662 (Baxter et al), and U.S. Pat.No. 4,172,468 (Ruus). These devices all suffer from one or more of thefollowing drawbacks: relatively massive pistons resulting in slowerresponse times, relatively elongated bodies, complicated constructionresulting in increased cost, or construction preventing positioning ofthe devices in different locations in existing systems.

Acomb discloses an anti-surge oxygen cylinder valve in which thesurge-suppression device is integrated with the cylinder valve. Thedevice referred to by Acomb requires a force opposed to a spring forceto function. In the Acomb device, the opposing force is provided by astem connected to the valve handle. Additionally, if the bleeder orificebecomes plugged, the valve does not allow flow, and the gas supply isnot available for use. In that case, the user may interpret the tank tobe empty when it is full, with the danger that such a misunderstandingbrings.

Baxter discloses a pressure shock absorber for a welding system. Baxterrefers to a piston that is elongated with a bore through the center. Theelongated piston results in an increased moment of inertia thatincreases the time in which the piston reacts to a pressure surge. Thelong bore results in necessarily tighter tolerances for controlling thegas flow rate through the bore. In addition, the placement of the springabutting the elongated piston results in a relatively large device.

Ruus discloses a pressure shock absorber for an oxygen-regulator supplysystem with an elongated, two-part piston. The elongate construction ofthe piston results in an increased moment of inertia that increases thetime required for the piston to react to a pressure surge. The two-partpiston results in increased complexity and manufacturing cost. Also inthis device, if the restricted passageway becomes plugged, no flow isallowed and the device suffers from the same potential for usermisinterpretation as the Acomb device.

SUMMARY OF INVENTION

The present invention overcomes to a great extent the deficiencies ofthe prior art by providing a device that has a first flow path forflowing gas at a first flow rate, a second flow path for flowing gas ata greater flow rate, and a handle that moves in a first direction toopen the first flow path and enable opening of the second flow path, andin a second direction to open the second flow path. In a preferredembodiment of the invention, the device may be a surge prevention valve.

According to one aspect of the invention, the handle moves in an axialdirection to open the first flow path, and in a rotational direction toopen the second flow path. In a preferred embodiment of the invention,the axial motion of the handle may be required to enable opening of thesecond flow path. The present invention should not be limited, however,to the preferred embodiments shown and described in detail herein.

According to another aspect of the invention, a spring may be used tobias the handle member in a direction opposite to the first direction.In addition, an engageable torque unit may be employed to transmittorque from the handle to open the second flow path. In a preferredembodiment of the invention, the spring is compressed to engage thetorque unit.

The present invention also relates to a surge prevention valve, such asa valve for use with a high pressure gas cylinder. The surge preventionvalve may have a housing with an inlet and an outlet. A seal unit may beused to close the flow path from the inlet to the outlet, and a bleedpassageway may be provided in the seal unit. The valve also may have anactuator for opening the bleed pathway and for moving the seal unit toopen the main flow path.

If desired, the seal unit may be threaded into the housing. With thisconstruction, the actuator may be used to threadedly move the seal unittoward and away from the valve seat to close and open the main flowpath. In addition, a valve rod may be provided for closing the bleedpassageway. The valve rod may be slidably located within the seal unit.

The present invention also relates to a method of operating a highpressure valve. The method includes the steps of: (1) moving a handle inan enabling direction to cause gas to flow through a first path at afirst flow rate; and then (2) moving the handle in a second direction tocause gas to flow through a second path at a much greater flow rate. Themethod also may include the step of closing the valve. According to apreferred embodiment of the invention, the method may involve flowinggas, such as oxygen or nitrous oxide, through a pressure regulator to auser or to an intended device (such as a respirator). The method may beused to gradually increase the flow rate into the regulator and toprevent the formation of a high pressure surge in the system.

According to another preferred embodiment of the present invention, amethod of opening a valve includes the steps of: (1) moving a handlebutton, within the handle, in an enabling direction to cause gas to flowthrough a first path at a first flow rate; and then (2) moving theentire handle in a second direction to cause gas to flow through asecond path at a much greater flow rate. According to one aspect of theinvention, the enabling direction may be an axial direction, and thesecond direction may be a rotational direction.

The present invention further relates to a surge prevention dual-port(or dual-path) valve, which is provided with first and second valveslocated within a housing and integrating a pressurization orifice. Theinitial opening of the dual-port (or dual-path) valve in an axialdirection enables a first flow of gas to flow through the pressurizationorifice at a first flow rate. The full opening of the dual-port (ordual-path) valve enables a second flow of gas to flow through the secondvalve at a second flow rate which is higher than the first flow rate.The controlled pressurization of the gas through the pressurizationcontrol orifice delays the time in which the gas reaches fullrecompression. This, in turn, allows the heat generated by the nearadiabatic process of the recompression of the gas to be dispersed. Thisway, high pressure surges are prevented, the heat during gasrecompression is dispersed and excessive heating is avoided. The presentinvention also relates to a method of operating the dual-port (ordual-path) valve.

In a preferred embodiment of the invention, the device has two separateports or seats, to define two respective flow paths. The first port/seatis a bleed port that is sized to pressurize an attached oxygen regulatorin greater than 0.250 seconds. The first port/seat is opened during theinitial actuation of the valve. The second (main) port/seat is openedduring the continuing actuation of the valve. If desired, the device maybe constructed to require enough motion so that, without the use of amechanical drive system, the valve cannot be opened fast enough tooverride the bleed function.

According to another aspect of the invention, the main port may be heldin place by a spring (such as a coil compression spring) surrounding theactuator) that is sized to overcome the source of pressure and tomaintain a gas-tight seal on the main port. According to this aspect ofthe invention, during the bleed portion of the valve actuation process,the main port is not influenced by the actuating stem.

According to yet another aspect of the invention, the main port isopened as the actuating stem re-engages the main seat carrier by meansof a stop which then allows the seat carrier to be driven open againstthe force of the spring (by further rotation of the actuator). In apreferred embodiment of the invention, the spring is compressed as theseat carrier is driven open.

In yet another embodiment of the invention, a surge prevention dual-port(or dual-path) valve provided with first and second valves locatedwithin a housing and integrating a pressurization orifice is furtherprovided with one or more sealing grooves and at least one vent orificefor venting pressurized oxygen away from a top surface of the lowervalve element.

In another embodiment of the invention, a gas supply system is providedwith a valve system having a valve inlet tube extending into a gascylinder to prevent particles and/or impurities from entering the valvesystem.

These and other objects and advantages of the invention may be bestunderstood with reference to the following detailed description ofpreferred embodiments of the invention, the appended claims and theseveral drawings attached hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an oxygen supply system constructed inaccordance with a preferred embodiment of the invention.

FIG. 2 is a cross-sectional view of a surge prevention valve for thesystem of FIG. 1, taken along the line 2—2 of FIG. 1.

FIG. 3 is another cross-sectional view of the surge prevention valve ofFIG. 2, at a subsequent stage of operation.

FIG. 4 is yet another cross-sectional view of the surge prevention valveof FIG. 2, at yet another stage of operation.

FIG. 5 is a cross sectional view of a surge prevention valve constructedin accordance with another preferred embodiment of the invention.

FIG. 6 is an expanded view of a lower section of the surge preventionvalve of FIG. 5.

FIG. 7 is another cross sectional view of the surge prevention valve ofFIG. 5, at a subsequent stage of operation.

FIG. 8 is yet another cross sectional view of the surge prevention valveof FIG. 5, at yet another stage of operation.

FIG. 9 is a cross sectional view of a dual-port surge prevention valveconstructed in accordance with another embodiment of the presentinvention.

FIG. 10 is a cross-sectional view of a dual-port surge prevention valveconstructed in accordance with another embodiment of the presentinvention.

FIG. 11 is a cross-sectional view of an oxygen supply system constructedin accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, where like elements are designated bylike reference numerals, there is shown in FIG. 1 an oxygen supplysystem 10 constructed in accordance with a preferred embodiment of thepresent invention. A detailed description of the illustrated system 10is provided below. The present invention should not be limited, however,to the specific features of the illustrated system 10.

Referring now to FIG. 1, the oxygen supply system 10 includes a pressureregulator 12, a conduit 14 for flowing oxygen from the pressureregulator 12 to a patient (not illustrated), a source of oxygen 16, anda post valve 20 for preventing oxygen from flowing out of the source 16.The source 16 may be an oxygen cylinder, for example. As discussed inmore detail below, the valve 20 may be arranged to prevent a highpressure surge from occurring in the pressure regulator 12 when thevalve 20 is opened. In addition to oxygen, the present invention may bealso used to handle nitrous oxide and other concentrated oxidizingagents, as well as other gas combinations used in the industry. Thepresent invention may also be used in systems other than medicalsystems. For example, the present invention may be applicable to oxygenwelding equipment.

Referring now to FIG. 2, the valve 20 includes a housing 22 having aninlet 24 and an outlet 26. The inlet 24 may be connected to the oxygensource 16. The outlet 26 may be connected to the pressure regulator 12.In addition, the valve 20 includes a seal unit 28, a valve rod 30, andan actuator unit 32. The seal unit 28 may have an annular elastomericseal pad 34 for sealing against a valve seat 36. A passageway 37 may beprovided to allow oxygen to flow through the pad 34 and into a firstbypass space 38 within the seal unit 28. The seal unit 28 also has asecond bypass space 40 and a bleed passageway 42.

The upper end 44 of the valve rod 30 is fixed within the actuator unit32. The lower portion of the valve rod 30 is slidably located within thesecond bypass space 40. The valve rod 30 may have a reduced diameterportion 46 and a conical lower end 48. Except for the reduced diameterportion 46 and the lower end 48, the remainder of the valve rod 30 mayhave a circular cross-section with a substantially constant diameter.The cross-sectional configuration of the valve rod 30 is such that anupper opening 50 of the first bypass space 38 is sealed by the lower end48 of the rod 30 in the position shown in FIG. 2.

As discussed in more detail below, the valve rod 30 may be moved downand through the seal unit 28 to the position shown in FIG. 3. In theFIG. 3 position, the reduced diameter portion 46 is located in the upperopening 50 of the first bypass space 38. The cross-sectional area of thereduced diameter portion 46 is less than that of the upper opening 50.Consequently, oxygen may flow through the upper opening 50 when thevalve rod 30 is in the FIG. 3 position.

The seal unit 28 is connected to the housing 22 by suitable threads 62.The threads 62 are arranged such that rotating the seal unit 28 withrespect to the housing 22 in a first direction moves the seal pad 34into sealing engagement with the valve seat 36. Rotating the seal unit28 in the opposite direction causes the seal pad 34 to move away fromthe valve seat 36 to the open position shown in FIG. 4. In the openposition, oxygen is allowed to flow through the valve seat 36, aroundthe seal unit 28 in the direction of arrow 64 and into the outlet 26. Ano-ring 66 or other suitable seal may be provided between the seal unit28 and the housing 22 for preventing oxygen from flowing around the sealunit 28 above the outlet 26.

The actuator unit 32 has a piston unit 70, a handle 72 fixed to thepiston unit 70, and a cover 74. The piston unit 70 is slidably locatedin the cover 74. The piston unit 70 is also allowed to rotate within thecover 74 as described in more detail below. The piston unit 70 is biasedupwardly (away from the seal unit 28) by a coil spring 76. The cover 74may be threaded into the housing 22, if desired.

A torque unit is formed by openings 78, 80 formed in the piston unit 70and pins 82, 84 fixed with respect to the seal unit 28. As shown in FIG.3, the pins 82, 84 may be received within the openings 78, 80 when thepiston unit 70 is pushed downwardly against the bias of the spring 76.When the pins 82, 84 are received within the openings 78, 80, a torqueapplied to the handle 72 may be transmitted to the seal unit 28. Thus, atorque may be manually applied to the handle 72 in a first direction tocause the seal unit 28 to move further down into the housing 22 to pressthe seal pad 34 into the sealed position shown in FIG. 2. In addition, atorque may be applied in the opposite direction to threadedly move theseal pad 34 away from the valve seat 36 to the open position shown inFIG. 4.

The present invention should not be limited to the specific features andinstrumentalities of the surge prevention valve 20 described and shownherein. Thus, for example, the torque unit may be formed by openings inthe seal unit 28 and pins fixed to the piston unit 70, and a variety ofother devices and mechanisms may be used to practice the presentinvention.

Thus, the valve 20 is closed in the position shown in FIG. 2. In theclosed position, oxygen cannot flow between the seal pad 34 and thevalve seat 36. In addition, in the closed position, the valve rod 30seals the upper opening 50 of the first bypass space 38, such thatoxygen cannot flow into the second bypass space 40. A suitable o-ring 88may be provided to form a gas-tight seal against the valve rod 30 in theupper opening 50, if desired.

The valve 20 is open in the position shown in FIG. 4. In the openposition, as mentioned above, oxygen can flow through the valve seat 36,around the seal unit 28 in the direction of arrow 64, and through thevalve outlet 26. To move the valve 20 from the closed position to theopen position, the user first pushes down manually on the handle 72,against the bias of the spring 76, until the pins 82, 84 are located inthe openings 78, 80. Pushing down on the handle 72 causes the pistonunit 72 to move axially toward the seal unit 28. Then the user appliestorque to the handle 72 in an opening rotational direction to threadedlyrotate the seal unit 28 away from the valve seat 36. The torque istransmitted through the piston unit 70 and through the torque unit 78–84to rotate the threaded seal unit 28. In the illustrated arrangement, theseal unit 28 cannot be rotated by the handle 72 unless the torque unit78–84 is engaged, with the spring 76 in the compressed position shown inFIG. 3. The torque unit 78–84 is engaged to enable rotation of the sealunit 28.

Pushing down on the handle 72 to engage the torque unit 78–84 causes thereduced diameter portion 46 of the valve rod 30 to move into the upperopening 50 of the first bypass space 38. When the reduced diameterportion 46 is in the upper opening 50, oxygen may flow into the secondbypass space 40 and through the bleed passageway 42. Oxygen can start toflow through the upper opening 50 while the handle 72 is movingdownwardly, before the torque unit 78–84 is fully engaged. In theillustrated arrangement, the handle 72 must be moved to the intermediateFIG. 3 position before the seal unit 28 can be threadedly lifted fromthe valve seat 36. Opening the valve 20 requires a two-step sequentialpush-then-twist operation much like the two-step operation required toopen safety caps on medicine bottles. If the user does not push down onthe handle 72, the piston unit 70 merely rotates within the cover 74without engaging the seal unit 28. However, this invention is notlimited to the preferred embodiment discussed herein.

Consequently, the illustrated valve 20 allows oxygen to bleed into theoutlet 26 through the bleed passageway 42 before the seal pad 34 ismoved away from the valve seat 36. The small amount of oxygen thatbleeds through the restricted passageway 42 during the short timerequired to engage the torque unit 78–84 may be sufficient to prevent ahigh pressure surge from developing in the system 10 when the valve 20is subsequently opened. Thus, the regulator 12 (FIG. 1) may be filled ata relatively slow, controlled rate before a fill flow of high pressureoxygen is allowed through the valve 20. The oxygen flow rate through thevalve seat 36 in the valve open position (FIG. 4) may be much greaterthan the flow rate through the bleed passageway 42 in the intermediateposition shown in FIG. 3.

In the preferred method of operation, the user will first push handle 72until the pressure stabilizes in the valve 20. This will open the firstflow path 38 and allow oxygen to flow at a reduced rate. The time ittakes to push the handle 72 down to enable opening of the valve 20 maybe sufficient for the desired gradual pressurization of the regulator12. The ability of the valve 20 to bleed sufficient oxygen into theoutlet 26 in the available time may be controlled, for example, byselecting a suitable cross-sectional area for the bleed passageway 42.The bleed passageway 42 may be formed by drilling the desired openinginto the seal unit 28, if desired. Larger or smaller drills may formlarger or smaller bleed passageways.

If the user intends to bypass the preferred method of operation or ifthe first bypass space 38 or bleed passageway 42 should become clogged,there will still be an added safety factor as long as the user slowlytwists the handle 72. Consequently, if desired, the user may beinstructed to twist the handle 72 slowly. If such instructions regardingthe twisting of the handle 72 are properly followed, the valve 20 maystill prevent a high pressure surge in the regulator 12 even without theassistance of the first bypass space 38 or bleed passageway 42. Thepresent invention should not be limited, however, to the specific valve34, 36 and bleed passageway 42 arrangement shown and described in detailherein.

In the open position shown in FIG. 4, substantially all of the oxygenflowing through the valve 20 travels in the direction of arrow 64 andnot through the bleed passageway 42. Consequently, the bleed passageway42 does not tend to become occluded by small contaminant particlesentrained in the gas flow. If the bleed passageway 42 becomes plugged,the valve 20 will still be operable so that oxygen is still supplied tothe intended operative device, such as a face mask for the patient, or acannula inserted into the patient.

To close the valve 20, the user pushes down on the handle 72, againstthe bias of the spring 76, to engage the torque unit 78–84. Then, whilethe spring 76 is compressed, the user manually twists the handle 72 tothreadedly move the seal unit 28 back into sealing contact with thevalve seat 36. Then the downward pressure on the handle 72 is released,such that the spring 76 draws the end 48 of the valve rod 30 back into asealed position within the upper opening 50 of the first bypass space38.

FIG. 5 illustrates a valve 100 constructed in accordance with anotherembodiment of the present invention which includes a housing 130 havingan inlet 140 and an outlet 114. The inlet 140 may be connected to theoxygen source 16. The outlet 114 may be connected to a pressureregulator 12. In addition, the valve 100 includes a seal unit 124, avalve rod 106, and an actuator unit 142. The seal unit 124 may have anannular elastomeric seal pad 144 for sealing against a valve seat 146. Afirst bypass 138 is provided to allow oxygen to flow through the pad 144to the seal unit 124. The seal unit 124 also has a bleed passageway 118.

The upper end 160 of the valve rod 106 is fixed within a handle button104. The lower portion of the valve rod 106 is slidably located within asecond bypass space 116 and a valve space 162. The valve rod 106 mayhave a reduced diameter portion 110 and a conical lower end 132. Exceptfor the reduced diameter portion 110 and the lower end 132, theremainder of the valve rod 106 may have a circular cross-section with asubstantially constant diameter. The cross-sectional configuration ofthe valve rod 106 is such that the o-ring 136 of the first bypass space138 seals the second bypass 116 from the first bypass 138 by the lowerend 132 of the rod 106 in the position shown in FIG. 5. As shown in FIG.6, the o-ring 136 combined with the lower end 132 of the valve rod 106may be the only components forming the seal 204 between the first bypassspace 138 and the second bypass space 116. Moreover, a continuouspassageway 202 is provided between the first bypass space 138 and theexposed lower surface of the o-ring 136 regardless of the location ofthe valve rod 106. Thus, gas may pass through the upper opening 164. Inthe illustrated system, the upper opening 164 serves as a backup platewhich keeps o-ring 136 from being blown into opening 128 in the eventthat someone tries to fill the gas source 16, without first openingvalve 100.

As discussed in more detail below, the valve rod 106 may be moved downand through the seal unit 124 to the position shown in FIG. 7. In theFIG. 7 position, the reduced diameter portion 110 is located in thefirst and second bypass spaces 138, 116. The cross-sectional area of thereduced diameter portion 110 is less than that of the first and secondbypasses 138, 116. Consequently, oxygen may flow through the first andsecond bypass openings 138, 116 when the valve rod 106 is in the FIG. 7position.

The seal unit 124 is connected to the housing 130 by suitable threads126. The threads 126 are arranged such that rotating the seal unit 124with respect to the housing 130 in a first direction moves the seal pad144 into sealing engagement with the valve seat 146. Rotating the sealunit 124 in the opposite direction causes the seal pad 144 to move awayfrom the valve seat 146 to the open position shown in FIG. 8. In theopen position, oxygen is allowed to flow through the valve seat 146,around the seal unit 124 in the direction of arrow 170 and into theoutlet 114.

The actuator unit 142 has a handle button 104, a handle 102 surroundingthe handle button 104, a socket structure 112, and a handle cover 154.The handle button 104 and the socket structure 112 are biased upwardly(away from the seal unit 124) by a coil spring 108. The cover 154 may bethreaded into the housing 130, if desired.

A torque unit is formed by pins 120, 156 formed in the handle 152 andpins 122, 158 fixed with respect to the seal unit 124 together withsocket structure 112. As shown in FIG. 7, the four pins 122, 158, 120,156 may be received by the socket structure 112 when the handle button104 is pushed downwardly against the bias of the spring 108. In the FIG.7 position, the socket structure 112 causes the pins 122, 158, 120, 156to move as one unit. Therefore, a torque applied to the handle 102 maybe transmitted to the seal unit 124. Thus, a torque may be manuallyapplied to the handle 102 in a first direction to cause the seal unit124 to move further down into the housing 130 to press the seal pad 144into the sealed position shown in FIG. 7. In addition, a torque may beapplied in the opposite direction to threadedly move the seal pad 144away from the valve seat 146 to the open position shown in FIG. 8.

The valve 100 is closed in the position shown in FIG. 5. In the closedposition, oxygen cannot flow between the seal pad 144 and the valve seat146. In addition, in the closed position, the o-ring 136 and the valverod 106 seal the first bypass space 138, such that oxygen cannot flowinto the second bypass space 116. As noted above, a suitable o-ring 136may be provided to form a gas-tight seal against the valve rod 106 inthe upper opening 164, if desired.

The valve 100 is open in the position shown in FIG. 8. In the openposition, as mentioned above, oxygen can flow through the valve seat146, around the seal unit 124 in the direction of arrow 170, and throughthe valve outlet 114. To move the valve 100 from the closed position tothe open position, the user first pushes down manually on the handlebutton 104, against the bias of the spring 108. Since the socketstructure 112 is integrated with the valve rod 106, the socket structure112 also moves down to the enclosing position against the bias of thespring 108. The socket structure 112 may be fixed with respect to thevalve rod 106 by a force fit or by adhesive, for example.

Pushing down on the handle button 104 causes the valve rod 106 to moveaxially toward the seal unit 124 and causes the pins 122, 158, 120, 156to become engaged within the socket structure 112. Then the user appliestorque to the handle 102 in an opening rotational direction tothreadedly rotate the seal unit 124 away from the valve seat 146. Thetorque is transmitted through the handle 102 and through the torque unit112, 120, 122, 156, 158, to rotate the threaded seal unit 124. In theillustrated arrangement, the seal unit 124 cannot be rotated by thehandle 102 unless the torque unit 112, 120, 122, 156, 158 is engaged,with the spring 108 in the compressed position shown in FIG. 7. Thetorque unit 112, 120, 122, 156, 158 is engaged to enable rotation of theseal unit 124. As shown in the drawings, the handle button 104 may beformed as part of the handle 102, and the button 104 may be locatedconveniently to be operated by the thumb of the hand that grips thehandle 102.

Pushing down on the handle button 104 to engage the torque unit 112,120, 122, 156, 158 causes the reduced diameter portion 110 of the valverod 106 to move into the upper opening 164 of the first bypass space138. When the reduced diameter portion 110 is in the upper opening 164,oxygen may flow into the second bypass space 116 and through the bleedpassageway 118. Oxygen can start to flow through the upper opening 164while the handle button 104 is moving downwardly, before the torque unit112, 120, 122, 156, 158 is fully engaged. In the illustratedarrangement, the handle button 104 must be moved to the intermediateFIG. 7 position before the seal unit 124 can be threadedly lifted fromthe valve seat 138. Opening the valve 100 requires a two-step sequentialpush-then-twist operation. If the user does not push down on the handlebutton 104, the handle 102 merely rotates within the cover 154 withoutengaging the seal unit 124.

Consequently, the illustrated valve 100 allows oxygen to bleed into theoutlet 114 through the bleed passageway 118 before the seal pad 144 ismoved away from the valve seat 146. The small amount of oxygen thatbleeds through the restricted passageway 118 during the short timerequired to engage the torque unit 112, 120, 122, 156, 158 may besufficient to prevent a high pressure surge from developing in thesystem 10 when the valve 100 is subsequently opened. Thus, the regulator12 (FIG. 1) may be filled at a relatively slow, controlled rate before afull flow of high pressure oxygen is allowed through the valve 100. Theoxygen flow rate through the valve seat 146 in the valve open position(FIG. 8) may be much greater than the flow rate through the bleedpassageway 118 in the intermediate position shown in FIG. 7.

In the preferred method of operation, the user will first push handlebutton 104 until the pressure stabilizes in the valve 100. The time ittakes to push the handle button 104 down to enable opening of the valve100 may be sufficient for the desired gradual pressurization of theregulator 12. The ability of the valve 100 to bleed sufficient oxygeninto the outlet 114 in the available time may be controlled, forexample, by selecting a suitable cross-sectional area for the bleedpassageway 118.

In the open position shown in FIG. 8, substantially all of the oxygenflowing through the valve 100 travels in the direction of arrow 170 andnot through the bleed passageway 118. Consequently, the bleed passageway118 does not tend to become occluded by small contaminant particlesentrained in the gas flow. If the bleed passageway 118 becomes plugged,the valve 100 will still be operable so that oxygen is still supplied tothe intended operative device.

To close the valve 100, the user may grip the handle 102 andsimultaneously depress the handle button 104, against the bias of thespring 108, to engage the torque unit 112, 120, 122, 156, 158. Then,while the spring 108 is compressed, the user manually twists the handle102 to threadedly move the seal unit 124 back into sealing contact withthe valve seat 146. Then the downward pressure on the handle button 104is released, such that the spring 108 draws the end 132 of the valve rod106 back into a sealed position with o-ring 136 within the upper opening164 of the first bypass space 138.

FIG. 9 illustrates a dual-port (or dual-path) valve 300 constructed inaccordance with another embodiment of the present invention. Asillustrated in FIG. 9, the dual-port (or dual-path) valve 300 includes ahousing 322 having an inlet 324 and an outlet 326. The inlet 324 may beconnected to the oxygen source 16 (FIG. 1). The outlet 326 may beconnected to the pressure regulator 12 (FIG. 1). The housing 322 ispreferably provided with wrench flats (not shown). The dual-port (ordual-path) valve 300 further includes an actuator unit 332, which inturn is provided with a cover 374 and an actuator body 333. The actuatorbody 333 has an inner surface 335 which is provided with threads 336.The actuator body 333 is connected to the housing 332 by suitablethreads 334. The lower end surface of the actuator body 333 provides anupper limit for a coil compression spring 391.

As also illustrated in FIG. 9, the actuator unit 332 has a piston unit370 which is rotatably and threadedly located in the cover 374. Athreaded center section 371 of the piston unit 370 is connected to theactuator body 333 by suitable threads 372 corresponding to the threads336 of the inner surface 335. As described in more detail below, thepiston unit 370 is rotatable within the actuator body 333.

A lower portion 377 of the piston unit 370 is slidably located within aspace 340 of a lower cup-shaped valve element 360, which in turn islocated within the housing 322. The lower portion 377 of the piston unit370 is provided with an elastomeric upper seat 350 which rests on afirst valve seat 351 of a first (upper) valve 355. A washer 341 islocated on the upper surface of the lower portion 377 of the piston unit370. Except for the lower portion 377 of the piston unit 370, theremainder of the piston unit 370 may have a cross-section with asubstantially constant diameter. (The terms “upper” and “lower” arerelative terms used herein for convenience in connection with FIG. 9.The device of FIG. 9 will operate in a horizontal position as well as inother orientations besides that shown in FIG. 9.)

The lower cup-shaped valve element 360 is further provided with a second(lower) valve 366 comprising a lower elastomeric, annular seat 395 whichrests on a second annular valve seat 376. The first (upper) valve 355and the second (lower) valve 366 integrate a pressurization controlorifice 380. The lower cup-shaped valve element 360 is further providedwith a lower stem seat 390 which is biased downwardly by the coilcompression spring 391. Annular elastomeric seal pads 381 and 382 may beprovided for sealing against the first valve seat 351 and the secondvalve seat 376, respectively.

The valve 300 is closed in the position shown in FIG. 9. In the closedposition, oxygen cannot flow between the seal pad 381 and the secondvalve seat 376. In addition, in the closed position, the first valveseat 351 seals the upper portion of the pressurization control orifice380. In the closed position, oxygen cannot bleed upwardly through thesmall control orifice 380.

In operation, the valve 300 is initially opened by rotating the threadedcenter post 371 of the piston unit 370 upward. A suitable handle 370Afor rotating the piston unit 370 may be attached to the top end of thepiston unit 370. When the user first rotates the threaded center section371, the upper seat 350 moves upwardly, in an axial direction. As aresult, the first (upper) valve 355 opens and allows the pressurizationcontrol orifice 380 to be in fluid communication with the outlet 326.This, in turn, will open a first flow path in the direction of arrow 393and allow oxygen to flow at a reduced rate.

As the user further rotates the threaded center section 371, the lowerportion 377 of the piston unit 370 continues to move upwardly in anaxial direction, and travels a distance “D” which is the height of thespace 340 of the lower cup-shaped valve element 360. This way, the uppersurface of the washer 341 contacts retaining clip 342 of the lowercup-shaped valve element 360 so that the lower portion 377 of the pistonunit 370 interlocks with the retaining clip 342 in a first axialposition.

The time it takes the lower portion 377 of the piston unit 370 to travelthe distance D within the space 340 to the first axial position may besufficient for the slow and gradual pressurization of the regulator 12(FIG. 1). The time it takes the lower portion 377 of the piston unit 370to travel the distance D to the first axial position, and thus tocompletely open the first (upper) valve 355 and to start opening thesecond (lower) valve 366, is preferably in the range of about 0.25seconds to about 1.5 seconds, and more preferably in the range of about0.5 seconds to about 1.25 seconds. The above range of time required forthe complete opening of the first (upper) valve 355 can, if desired, becorrelated to the amount of handle rotation required to start theopening of the second valve 366, by controlling the spacing (pitch) ofthe engaged threads 372, 336 of the actuator body 333 and inner surface335.

For example, the spacing (pitch) of the threads 372, 336 may be set suchthat the piston unit 370 has to be rotated in the range of at leastabout 270 degrees to about 450 degrees, more preferably at least about270 degrees to about 360 degrees, to allow the second (lower) valve 366to start opening. To rotate the piston unit 370 through at least 270degrees, a typical user is required to remove his/her hand from theoxygen tank valve handle 370A and to re-grip the handle 370A to completethe opening process. It would be awkward and unusual for the typicaluser to rotate the handle 370A through 270 degrees without removing hisor her hand from the handle 370A at least once. The time it takes thetypical operator to release and re-grip the handle 370A, to accomplishrotation of the handle through 270 degrees or more, is at least about0.25 seconds. Accordingly, in the preferred embodiment of the invention,the time it takes the piston unit 370 to rotate through at least about270 degrees, to start the opening of the second (lower) valve 366 is atleast 0.25 seconds.

The ability of the first (upper) valve 355 to bleed sufficient oxygeninto the outlet 326 may be further controlled, for example, by selectinga suitable cross-sectional area for the pressurization control orifice380. In any event, the regulator 12 (FIG. 1) may be filled at arelatively slow and controlled rate before a full flow of high pressureoxygen is allowed through the valve 300.

While the piston unit 370 travels distance D within the space 340 to thefirst axial position, the coil compression spring 391 holds the lowerstem seat 390 of the lower cup-shaped valve element 360 in a closedposition (biased downwardly against the second valve seat 376). As aresult, the second valve seat 376 of the second (lower) valve 366remains closed and oxygen cannot flow between the seal pad 381 and thesecond valve seat 376.

As the user subsequently rotates the threaded center section 371, thelower cup-shaped valve element 360, which becomes interlocked with thelower portion of the piston unit 370 through retaining clip 342, isretracted from the first axial position (i.e., the illustrated position)to a second axial position. Consequently, the lower seat 395 lifts offthe second valve seat 376 and the second (lower) valve 366 is open. Thisway, in the fill open position, substantially all of the oxygen isallowed to flow through the second (lower) valve 366 of the dual-portvalve 300 in the direction of arrow 399.

The multi-path valve 300 of FIG. 9 provides a controlled pressurizationof gases and prevents a high pressure surge from occurring in thepressure regulator 12 (FIG. 1) when the valve 300 is initially opened.The controlled initial bleeding of the gas through the pressurizationcontrol orifice 380 (FIG. 9) delays the time in which the gas (e.g.oxygen) reaches full recompression. This, in turn, provides time for theheat generated by the recompression of the gas to be dispersed. Bypreventing high pressure surges and by dispersing heat during gasrecompression, the occurrence of excessive heat is avoided and,consequently, the possibility of ignition of the valve and/or regulatoris substantially eliminated.

FIG. 10 illustrates a dual-port (or dual-path) valve 400 constructed inaccordance with another embodiment of the present invention. Thedual-port (or dual-path) valve 400 is similar to the valve 300 of FIG. 9to the extent that the first (upper) valve 355 and the second (lower)valve 366 integrate or enclose a narrow passageway 380. As described inmore detail below, however, the dual-port (or dual-path) valve 400 ofFIG. 10 has additional features and structures for venting pressurizedoxygen supplied by the oxygen source 16 (FIG. 1) away from a top surface495 a of the second (lower) valve 366.

As illustrated in FIG. 10, the valve 400 includes housing 322 having aninlet 324 and an outlet 326. As in the previously described embodiment,the inlet 324 may be connected to the oxygen source 16 (FIG. 1) and theoutlet 326 may be connected to the pressure regulator 12 (FIG. 1). Theinlet 324 may have a diameter as small as possible, but not smaller thanCGA V-1 Standards (October 1994, revised January 1996). The valve 400further includes an actuator unit 332, which in turn is provided with acover 374 (FIG. 9) and an actuator body 333. The lower end surface ofthe actuator body 333 provides an upper limit for the coil compressionspring 391. As also illustrated in FIG. 10, a threaded center section371 of the piston unit 370 is connected to the actuator body 333 bysuitable threads. As described above with reference to the valve 300 ofFIG. 9, the piston unit 370 is rotatable within the actuator body 333.

The lower portion 377 of the piston unit 370 is slidably located withinspace 340 of a lower cup-shaped valve element 460, which in turn islocated within the housing 322. The lower-cup shaped valve element 460is further provided with a lower stem seat 390 which is biaseddownwardly by the coil compression spring 391. The lower portion 377 ofthe piston unit 370 is also provided with an annular elastomeric upperseat 450 which rests on a first valve seat 351 of a first (upper) valve355. As illustrated in FIG. 10, the annular elastomeric upper seat 450has a ring shape configuration that confers a localized yet uniformpressure upon the edges of the first valve seat 351 of the first (upper)valve 355. In this manner, the force that can be exerted on the firstvalve seat 351 is exerted only upon the edges of the seat, therebyincreasing the localized pressure exerted upon the first (upper) valve355.

As also illustrated in FIG. 10, there is a second outlet 426 providedwithin the actuator body 333. The second outlet 426 may provide anadditional path to a pressure regulator, such as the pressure regulator12 of FIG. 1.

The lower-cup shaped valve element 460 of FIG. 10 is further providedwith a second (lower) valve 366. The lower valve 366 includes aring-shaped elastomeric element 495. When the valve 366 is closed, thering-shaped elastomeric element 495 rests on a second valve seat 376. Anannular sealing groove 410 is located adjacent to the upper surface 495a of the ring-shaped elastomeric element 495. A vent orifice 420 isconnected to the annular sealing groove 410. The vent orifice 420extends from the annular sealing groove 410 to a lower seat area 441.The vent orifice 420 allows oxygen to flow from the sealing groove 410to the lower seat area 441. The lower valve 366 also includes a filterelement 388, which prevents debris and contaminated impurities andparticles from entering the vent orifice 420.

During the opening of the first (upper) valve 355 but before the openingof the second (lower) valve 366, oxygen might be able to leak out of thecylinder 16 (FIG. 1) through space between the top surface of thering-shaped elastomeric element 495 and an adjacent bottom surface ofthe valve element 460. The high pressure oxygen (if it were not vented)could tend to push the elastomeric element 495 out of the valve element(downward as shown in FIG. 10). By providing the annular sealing groove410 in communication with the vent orifice 420 and the lower seat area441, the high pressure oxygen is vented into the lower seat area 441.

Thus, ring-shaped area A₁ (FIG. 10) defined within the inner diameter D₁(FIG. 10) of the sealing groove 410 is the only area that can besubjected to a high pressure from leaking oxygen. The groove 410 and theradially extending vent orifice 420 operate as a pressure reliefpassageway to prevent a high differential pressure from accumulatingover the rest of the surface of the elastomeric element 495, in otherwords, area A₂ (FIG. 10) defined between the periphery of theelastomeric element 495 (having diameter D₃) and the periphery of thesealing groove 410 (having diameter D₂), will remain at the samepressure as the lower seat area 441. Accordingly, oxygen in the area A₂cannot exert any downward force upon the elastomeric element 495.

In addition, the inner diameter D₁ of the sealing groove 410 can beselected so that the equal but opposite upward force applied to thevalve element 460 by high pressure oxygen cannot overcome the forceexerted by the coil compression spring 391. This additional featureprevents the lower elastomeric seat 495 from coming out of itsillustrated location within the valve element 460. A lower annular edgeof the valve element 460 surrounds the lower surface of the elastomericelement 495. The lower annular edge (made of metal) can be crimpedradially inwardly to secure the elastomeric element 495 in itsillustrated location. The venting system 410, 420 can be especiallyuseful if the device 400 is made with either a poor crimp or no crimp atall, and it also provides safety advantages. If there is no crimpapplied to the elastomeric element 495, then the venting system 410, 420can help ensure that the elastomeric element 495 stays in its desiredposition.

As the user further rotates the threaded center section 371, thelower-cup shaped valve element 460 becomes interlocked with the lowerportion of the piston unit 370 and consequently the lower seat 495 liftsoff the second valve seat 376 and the second (lower) valve 366 is open.Thus, in fill open position, substantially all of the oxygen is allowedto flow through the second (lower) valve 366 of the dual-port valve 400in the direction of arrow 499.

FIG. 11 illustrates yet another embodiment of the invention, accordingto which gas supply system 500 is provided with a valve system 600 thatprevents particles and/or impurities from entering the valve system. Asillustrated in FIG. 11, the gas supply system 500 includes a source ofgas 160 and a conduit 14 for flowing gas from the source of gas 160 to apatient (not illustrated). As shown in FIG. 11, the source of gas 160may be an oxygen source, for example. The source of gas 160 of FIG. 11includes a gas container, for example a cylinder 510 which includes alower cylinder portion 501 and an upper cylinder portion 503 which has asmaller diameter than the diameter of the lower cylinder portion 501.The upper cylinder portion 503 has an inner surface 504 which isprovided with threads 505.

The valve system 600 comprises a valve unit 650 and a valve inlet 610.The valve unit 650 may comprise any of the valves 20, 100, 200, 300 and400, respectively, described above with reference to FIGS. 2–10. Forexample, the valve unit 650 may include the dual-port (or dual-path)valve 300 shown in FIG. 9.

As illustrated in FIG. 11, the valve inlet 610 has a tubular part 611connected to a threaded element 613. The tubular part 611 has a tubularconfiguration with a circular cross-section with a substantiallyconstant diameter. However, the tubular part 611 may have variousconfigurations, for example, rectangular, trapezoidal or elipsoidal,among many others. As shown in FIG. 11, the tubular part 611 extendsinto the gas cylinder 510. The tubular part 611 is provided with a gaspassageway 616. The tubular part 611 may have a length L (FIG. 11) ofabout 0.5 cm to about 10 cm, more preferably about 1 cm to about 2 cm(for a standard gas cylinder).

The threaded element 613 (FIG. 11) has an outer surface 614 which isprovided with suitable threads 605 that correspond to the threads 505 ofthe upper cylinder portion 503 of the cylinder 510. As illustrated inFIG. 11, the threaded element 613 is connected to the valve unit 650 byseal 507 and annular element 508.

The above-described embodiment provides the advantage that, when the gassupply system 500 is rotated in any of the three directions relative tothe position of FIG. 11, particles and/or impurities, such as metalscale, dust, etc., contained within the oxygen 160 are not caught in theoxygen stream that flows from the oxygen cylinder 510 and into gaspassageway 616. For example, when the gas supply system 500 is turnedupside down relative to the position of FIG. 11, the contaminantparticles are not caught in the oxygen stream flowing in the directionof arrow A (FIG. 11), but rather accumulate in the region A₁₀ defined bythe inner surface of the upper cylinder portion 503 and the outersurface of the tubular part 611. In this manner, the particles and/orimpurities are trapped in the region A₁₀, cannot enter the gaspassageway 616, and the valve orifices do not become plugged.

Although the embodiments of the present invention have been describedabove with reference to a supply system for oxygen, the invention is notlimited to oxygen or to an oxygen supply system. Thus, the invention isalso applicable to other gases, compositions of gases or gas systems,including but not limited to nitrous oxide and other gases mentioned inCGA V-1 Standards (October 1994, revised January 1996).

The above description and drawings are only illustrative of preferredembodiments which can achieve and provide the objects, features andadvantages of the present invention. It is not intended that theinvention be limited to the embodiments shown and described in detailherein. Modifications coming within the spirit and scope of thefollowing claims are to be considered part of the invention.

1. A fire prevention method of operating a medical oxygen deliverysystem, said method comprising the steps of: providing a cylindercontaining oxygen; providing a medical device for delivering said oxygento a patient; locating a valve between said oxygen cylinder and saidmedical device, said valve having a stem, and said stem having a reduceddiameter portion; opening said valve to a partially open condition bymoving said stem in a first direction such that said oxygen flows in asecond direction around said reduced diameter portion, said seconddirection being opposite said first direction; and subsequently, openingsaid valve to a condition that is more open than said partially opencondition.
 2. The method of claim 1, further comprising the steps ofpushing at least a portion of a handle in said first direction to opensaid valve to said partially open condition, and rotating said handle toopen said valve to said more open condition.
 3. A medical oxygendelivery system, comprising: a cylinder containing oxygen; a medicaldevice for delivering said oxygen to a patient; a fire prevention valvelocated between said oxygen cylinder and said medical device, said valvehaving a stem, and said stem having a reduced diameter portion, whereinsaid valve is arranged to be partially opened by moving said stem in afirst direction such that said oxygen flows in a second direction aroundsaid reduced diameter portion, said second direction being opposite saidfirst direction, and wherein said valve is arranged to be openedsubsequently to a condition that is more open than said partially opencondition.
 4. The system of claim 3, wherein said medical deviceincludes a pressure regulator.
 5. A fire prevention valve for a medicaloxygen delivery system, said valve comprising: a first end forconnection to a cylinder containing oxygen; a second end for connectionto a medical device for delivering said oxygen to a patient; and a stemhaving a reduced diameter portion, and wherein said valve is arranged tobe partially opened by moving said stem in a first direction such thatsaid oxygen flows in a second direction around said reduced diameterportion, said second direction being opposite said first direction, andwherein said valve is arranged to be opened subsequently to a conditionthat is more open than said partially open condition.
 6. The valve ofclaim 5, further comprising a rotatable handle for opening said valve tosaid more open condition.